Apple Watch ‘PTT’ Would Enable Quick Blood Pressure Readings

Apple’s latest patent, which was published on Thursday by the U.S. Patent and Trademark Office, details a novel new method by which the company’s Watch device can measure blood pressure using a connected accelerometer apparatus, via Patently Apple.

High blood pressure is among the leading causes of coronary heart disease and stroke, and its symptoms affect roughly one in three Americans, according to the CDC. While the medical field is ripe with management and prevention options for those with high blood pressure, it’s unfortunately a difficult symptom to quantify unless you have access to a cuff-based heart rate monitor system, or happen to frequent your local CVS for a free blood pressure test on their ‘arm-strangling machine’.

However in the medical field, this inflatable cuff system is actually the Gold standard for measuring blood pressure, and providing an accurate, decipherable reading. It achieves the feat by slowly inflating the cuff around (and cutting off circulation in) a person’s arm — ultimately measuring the point at which blood flow resumes, and again when it returns to normal. Though these systems are cumbersome, sophisticated, and expensive, Apple’s patent would suggest the company has at least entertained building a more user-friendly tool for measuring blood pressure with an Apple Watch.

Pulse Transit Time (PTT)

Titled “Wrist Worn Accelerometer for Pulse Transit Time (PTT) Measurements of Blood Pressure,” Apple’s patent No. 20170281024 describes a method of using an Apple Watch (in conjunction with a separate, accelerometer device) to detect heart rate and pulse — with the latter attachment being used to detect heartbeat at the chest, and Apple Watch’s heart rate sensor providing a pulse at the wrist.

And the underlying premise is simple, though it may seem confusing on paper.

Our hearts beat, which in turn causes blood to pump through our arteries with force and circulate throughout our body. So if you can detect a heart beat at the chest, and then detect the force (pulse) created by it in your wrist, you could ultimately measure the time it takes for the beat to get from point A to point B.

This variable is known as the Pulse Transit Time (PTT); and just like those big, bulky cuff machines at the drug store, it can also be used to provide an accurate calculation of blood pressure.

It’ll certainly be interesting to see what comes of this patent, especially since we know Apple is already hard at work on multiple digital health initiatives. And while the process of approving new medical tools and therapies at the Food and Drug Administration may be a tedious obstacle to overcome, recent reports suggest the FDA has been working to fast-track some of Apple’s most ambitious health projects, according to Bloomberg.